Sir Bruce Keogh also said that most local health authorities were not using the “best evidence” to base decisions on whether or not to fund surgery.

Labour said ministers should “act without delay” to remedy the situation.

Sir Bruce’s comments come months after a report by the Royal National Institute for Blind People (RNIB) found that 57 per cent of England’s 157 primary care trusts used eye test thresholds to determine who qualified for surgery.

In some parts of the South East, a patient's sight has to be so bad that they struggle to read the large letters on the third line down on a standard eye chart.

Sir Bruce told MPs on the Public Accounts Committee: “We do know that about 50 per cent of PCTs have restricted access to cataract surgery, and we do know that the bulk of policies used by PCTs actually haven’t used the best evidence that’s available in order to ration that care.”

He also said he had been “deluged” with complaints in late 2010 about different authorities setting different criteria for cataracts operations, hip and knee replacements, and other treatments.

Andy Burnham, the Shadow Health Secretary, said: “Finally, the Department of Health has admitted what Labour has been saying for months - that cataract surgery is being unfairly restricted.

“Ministers have promised to lift unfair restrictions. Now that the medical director of the NHS has confirmed it’s happening they must act without delay.”

Health authorities claim they are restricting access to ‘low clinical value’ treatments in cases where there is poor evidence of patient benefit. However, some have admitted rationing surgery for financial reasons.

Steve Winyard, head of policy and campaign at the RNIB, said restricted access to cataracts surgery was "forcing thousands of people to live with serious and unnecessary sight loss".

He said: "This admission by Sir Bruce Keogh further underlines the need for immediate action.

"We believe PCTs introducing thresholds to restrict access to cataract surgery do so without being able to demonstrate that they will not harm patients."

However, a Department of Health spokesman said Sir Bruce's comments "did not concern patient access to cataract surgery on the basis of cost, but on the basis of clinical eligibility, and the kinds of criteria that doctors in different parts of the country have been using".

He continued: "There is evidence of this going back several years - which is exactly why Sir Bruce is doing important work with the medical Royal Colleges and others, so that the NHS is clear about the evidence base for cataract surgery."

He added: "Restricting access to services on the basis of cost alone is wrong and compromises patient care."